1. Field of the Invention
The invention relates to a binding, especially for cross-country skis, for fixing a front section of a boot in such a way that during use the heel of the boot can be freely lifted off.
2. Description of the Related Art
Such bindings are generally known for skis intended for cross-country or touring use or for telemark sport. A binding designed for this purpose should be both simple in construction and reliable in function, during both cross-country and downhill skiing. Furthermore, a binding for touring or cross-country skiing should be ergonomically advantageous, enabling anatomically appropriate locomotor movements on skis.
This aim is attained with a ski binding of the kind mentioned above in that the boot becomes fixed to the binding firstly by a hooking or interlocking engagement of the sole of the boot, in the region between the ball and the front end and in particular in the toe-joint region of the sole, and secondly by means of a device that acts on the sole or on the boot, in particular in an elastic manner, so that the engagement remains secure during use.
This kind of attachment of a boot to a binding is extremely simple and nevertheless functions suitably. The boot is merely hooked into or interlocked with the binding, while each of the interlocking elements is an immobile part of the sole or binding, respectively. To keep the interlocking stable, of course, other means must be provided that act on the boot or its sole in such a way that the boot remains engaged during use. These means preferably comprise elastically pretensioned tensioning means, which when required simultaneously guide the boot laterally and stabilize it. This embodiment is particularly advantageous for downhill skiing.
Another embodiment of the structural principle in accordance with the invention is characterized in that the means acting on the sole or the boot keep it engaged with the binding by holding the front end of the sole down. As a result, the sole of the ski boot in the region between the engagement site and the front end is held firmly to the binding or its upper surface and a constant contact between boot and ski is ensured. This contact is also not broken when in the region between the engagement site and the front end of the sole an elastically yielding element, or flexor, is disposed between sole and binding.
The means acting on the sole or the boot in order to maintain the engagement can be either a tensioning cable that passes around the heel of the boot and keeps the boot in place by exerting a force that tends to pull it forward, or a tensioning cable that passes around the front end of the boot or its sole and keeps the boot in place by exerting a force directed towards the back.
When the front end of the sole is to be held down, it is preferable to use a closing element pivotably mounted on a U- or C-shaped swivel iron and connected to an actuating lever, such that the swivel iron is pivotably mounted on the binding near the sole engagement site and positioned below, about at the same level as, or just above the sole, so that the two arms of the swivel iron extend along the two lateral edges of the sole in a diagonally forward and upward direction, and stabilize the sole and hence the boot at the sides. The swivel iron thus has a double function: firstly it serves to hold the closing element, and secondly its arms simultaneously guide the boot laterally. It is also important that the coupling of the swivel iron is situated near the site of engagement of the sole, either just ahead of or just behind this site. By this means a functionally secure interlocking is achieved entirely by the closing element, with no need for the exertion of very high forces in order to actuate that element.
When in the locked position, the closing element is kept in a position beyond the dead point, where its axis of rotation is above the line connecting the site at which it abuts against the sole and the site at which the U- or C-shaped swivel iron is coupled to the binding. In order to open the closing element and hence the binding, the axis of rotation is brought into a position below said connecting line, by the appropriate imposition of force on an actuating lever connected to the closing element.
The interlocking elements are kept in the engaged position exclusively by the closing element. No separate closing elements in the sole region or on the underside of the sole are required for this purpose.
It should also be mentioned that the interlocking in the toe-joint region of the sole is particularly advantageous anatomically. As a result the foot is minimally constrained during the so-called diagonal step. Because of the additional lateral stabilization of the boot in the last-mentioned embodiment, this is also suitable for so-called skating and in particular for telemark sport.
The pivot bearing or the axis of rotation of the swivel iron is preferably adjustable in its height, in particular so that it can be positioned below the level of the sole, at the same level as the sole, or above it. These adjustments have an influence on the resistance moment when the heel of the boot is raised. The higher the coupling of the swivel iron is positioned, the more rapidly does the resistance moment rise.
In the case in which the means acting on the sole or the boot in order to maintain the interlocking comprises a tensioning cable that passes around the front end of the boot or of its sole, this cable too is coupled to a closing element, which preferably is disposed behind the boot and is accessible. The actual closing mechanism in this embodiment can be disposed below the sole, in particular below the heel of the boot, and can comprise an elbow-lever arrangement which can be brought into a beyond-dead-point closed position by pressing it down with the heel.
Alternatively, it is conceivable for the boot to be fixed to the binding by interlocking means (receiving openings) disposed in the sole-sided region between ball and front end of the sole, in particular in the toe-joint region of the sole, into which are inserted in a lock-like manner retaining hooks that are movably mounted on the binding side.
In principle it holds for all embodiments that for engagement of the sole, on the under surface thereof first interlocking elements are disposed that interact with complementary second interlocking elements on the binding in such a way that in the interlocked state the sole and hence the boot is held to the binding firmly, i.e. substantially without play.
As sole-sided interlocking elements there can be provided at least one, in particular two retaining hooks, which are bent backward and are preferably disposed near the edge of the sole, and which can be inserted into complementary receiving openings on the binding side. These are preferably formed by wire straps bent into approximately a U shape, each of which stands upright with its width oriented transversely with respect to the long direction of the ski or boot. These define openings directed forward and backward to receive the sole-sided retaining hooks.
It is further of quite crucial significance that the sole-sided interlocking elements are so disposed as to lie within the sole, so that they do not project beyond its tread, for which purpose they are situated within recesses in the sole that extend at least in the long direction of the sole. This measure ensures that normal walking while wearing the boot is not hampered by the interlocking elements. The associated recesses in the sole serve for collision-free engagement with the complementary interlocking elements on the binding side. Furthermore, snow or the like can be pushed out of the recesses during the engagement process, i.e. when the sole-sided interlocking elements are being inserted into the binding-sided receiving openings.
In principle it is also conceivable for the sole-sided interlocking elements to be engaged with complementary interlocking elements on the binding by merely inserting the boot and standing in or on the binding (step-in mechanism). However, it is then necessary to open this engagement mechanism manually in order to get out of the binding, for which a special handle is required.
The sole-sided interlocking elements can also consist of at least one, in particular two receiving slots, each disposed near the edge of the sole and opening towards the back, in the form of a receiving fork into which screws or the like disposed on the binding can be inserted in such a way that the heads of the screws overlap the receiving slots. This construction is an alternative to the construction previously described.
It is also conceivable to use as sole-sided interlocking elements at least one, in particular two cross-axles each disposed within a recess near the edge of the sole, which extend approximately parallel to the tread of the sole and can be inserted into hooks or straps that are bent forward and disposed on the binding, so as to become engaged therewith. Alternatively, the sole-sided interlocking elements can be constructed as a retaining iron bent into a U or C shape,
With the closing element that acts on the front end of the sole there is preferably also associated an elastic element against the action of which it can be moved past the dead-point line. This elastic element can be part of an arm of the swivel iron that holds the closing element. Alternatively, the elastic element can be disposed between the swivel iron and the closing element itself, as an elastic pressure element between swivel iron and closing element on the side thereof that faces the boot.
Finally, it should be pointed out that a ski brake can be associated with the binding, in particular a ski brake of the conventional kind, which when the boot is inserted into the binding and the front part of the sole is engaged therewith can be pivoted into an inactive travelling position against the action of a torsion spring, and does not return to the braking position until the boot is removed from the binding. For this purpose a sole-contact plate is coupled to the ski brake, at the front end of which a sole abutment is formed. When the boot enters the binding, the front end of the sole is brought into contact with said sole abutment. Then the sole-contact plate is pressed downward and simultaneously the ski brake pivots upward into the travelling position. After this the boot can be pulled backwards relative to the ski so that it interlocks with the binding. This engagement is secured by the closing element described above and its action on the front end of the sole.
Preferably the described interlocking and closing mechanism is situated on a plate that is fixed to the upper surface of the ski or to a binding shell mounted thereon in such a way that it can be swung to the side under the action of a specified limiting torsional load; that is, it can rotate about an axis that is approximately perpendicular to the upper surface of the ski. As a result, the ski binding in accordance with the invention amounts to a safety binding, which is particularly attractive for telemark sport.